Name History
1953 – 1973: National Association for Retarded Children (NARC)
1973 – 1981: National Association for Retarded Citizens (NARC)
1981 – 1992: Association for Retarded Citizens of the United States (ARC)
1992 – Present: The Arc of the United States (The Arc)
https://thearc.org/about-us/history/
It was pretty common terminology up until the 90's, until pc started creeping in.